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Biologists Engineered An Assassin Virus to Kill Bacteria on Command

Listening In

Different viruses attack different types of cells. A flu virus, for example, attacks lung cells, while the HIV virus attacks immune-system cells. Some viruses, known as phages, attack bacteria — and, it turns out, they don’t all do so randomly.

A team from Princeton has discovered that some phages actually “listen” to the conversations that take place between bacteria to identify the ideal time to strike — and we might be able to use this discovery in the battle against antibiotic resistance.

Tiny Spy

We’ve long known that bacteria can communicate through the release of molecules. In a paper published in the journal Cell on Thursday, the Princeton researchers describe a finding that builds on that mechanism: a virus called VP882, which “listens” for those molecules in order to know when there are enough bacteria around to justify attacking, a process that involves creating many replicas of itself.

This eavesdropping is a survival technique — if there aren’t enough bacteria around, the VP882 virus and its replicas will all die after the attack. It turns out, VP882 isn’t unique, either. The Princeton team discovered that other viruses also spy on bacteria in various ways to determine when to strike.

“It’s brilliant and insidious!” researcher Bonnie Bassler said in a press release. It’s also the first known example of such radically different organisms listening to one another’s communications.

Assassins Freed

Once the Princeton team figured out VP882’s eavesdropping ability, it set out to use that ability against bacteria. By re-engineering VP882 in the lab, graduate student Justin Silpe was able to get the virus to attack when it sensed any input he chose, not just the communication molecule that naturally set it off.

And VP882 itself is unique in that it can infect multiple types of cells, unlike the flu and HIV viruses mentioned above. In tests, Silpe manage to get VP882 to attack cholera, salmonella, and E. coli — three very different types of bacteria.

The medical community already knew it could use some phages to treat bacterial diseases. Now that we know we can turn a least one phage into an assassin, we might be able to find a way to use it against the antibiotic-resistant bacteria currently threatening global health.